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Subject[RFC PATCH] cpuidle: allow per cpu latencies
Date
On some systems (eg Tegra30) latencies for a given C state are not equal for
all CPUs. Therefore we introduce a new per CPU structure which contains
those parameters.

--

This patch doesn't update all cpuidle device registrations. I will do that
in a next version after agreement on the exact data structure to be
introduced.

Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
---
arch/arm/mach-tegra/cpuidle.c | 15 +++++++++++----
drivers/cpuidle/cpuidle.c | 27 ++++++++++++++++++++++++---
drivers/cpuidle/driver.c | 25 -------------------------
drivers/cpuidle/governors/ladder.c | 21 ++++++++++++---------
drivers/cpuidle/governors/menu.c | 7 ++++---
drivers/cpuidle/sysfs.c | 34 +++++++++++++++++++++++-----------
include/linux/cpuidle.h | 17 ++++++++++-------
7 files changed, 84 insertions(+), 62 deletions(-)
diff --git a/arch/arm/mach-tegra/cpuidle.c b/arch/arm/mach-tegra/cpuidle.c
index d83a8c0..b8fdf02 100644
--- a/arch/arm/mach-tegra/cpuidle.c
+++ b/arch/arm/mach-tegra/cpuidle.c
@@ -41,14 +41,20 @@ struct cpuidle_driver tegra_idle_driver = {
.states = {
[0] = {
.enter = tegra_idle_enter_lp3,
- .exit_latency = 10,
- .target_residency = 10,
- .power_usage = 600,
- .flags = CPUIDLE_FLAG_TIME_VALID,
.name = "LP3",
.desc = "CPU flow-controlled",
},
},
+ .power_specified = 1,
+};
+
+static struct cpuidle_state_parameters __initdata tegra_idle_parameters[] = {
+ [0] = {
+ .exit_latency = 10,
+ .target_residency = 10,
+ .power_usage = 600,
+ .flags = CPUIDLE_FLAG_TIME_VALID,
+ },
};

static DEFINE_PER_CPU(struct cpuidle_device, tegra_idle_device);
@@ -95,6 +101,7 @@ static int __init tegra_cpuidle_init(void)
dev->cpu = cpu;

dev->state_count = drv->state_count;
+ dev->state_parameters[0] = tegra_idle_parameters[0];
ret = cpuidle_register_device(dev);
if (ret) {
pr_err("CPU%u: CPUidle device registration failed\n",
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 87411ce..b992d00 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -87,8 +87,9 @@ int cpuidle_play_dead(void)
for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
struct cpuidle_state *s = &drv->states[i];

- if (s->power_usage < power_usage && s->enter_dead) {
- power_usage = s->power_usage;
+ if (dev->state_parameters[i].power_usage < power_usage
+ && s->enter_dead) {
+ power_usage = dev->state_parameters[i].power_usage;
dead_state = i;
}
}
@@ -371,7 +372,7 @@ EXPORT_SYMBOL_GPL(cpuidle_disable_device);
*/
static int __cpuidle_register_device(struct cpuidle_device *dev)
{
- int ret;
+ int ret, i;
struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();

@@ -389,6 +390,26 @@ static int __cpuidle_register_device(struct cpuidle_device *dev)
return ret;
}

+ /*
+ * cpuidle driver should set the drv->power_specified bit
+ * before registering if the driver provides
+ * power_usage numbers.
+ *
+ * If power_specified is not set,
+ * we fill in power_usage with decreasing values as the
+ * cpuidle code has an implicit assumption that state Cn
+ * uses less power than C(n-1).
+ *
+ * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
+ * an power value of -1. So we use -2, -3, etc, for other
+ * c-states.
+ */
+ if (!cpuidle_driver->power_specified) {
+ for (i = CPUIDLE_DRIVER_STATE_START;
+ i < cpuidle_driver->state_count; i++)
+ dev->state_parameters[i].power_usage = -1 - i;
+ }
+
dev->registered = 1;
return 0;
}
diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 40cd3f3..d81c6db 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -17,30 +17,6 @@
static struct cpuidle_driver *cpuidle_curr_driver;
DEFINE_SPINLOCK(cpuidle_driver_lock);

-static void __cpuidle_register_driver(struct cpuidle_driver *drv)
-{
- int i;
- /*
- * cpuidle driver should set the drv->power_specified bit
- * before registering if the driver provides
- * power_usage numbers.
- *
- * If power_specified is not set,
- * we fill in power_usage with decreasing values as the
- * cpuidle code has an implicit assumption that state Cn
- * uses less power than C(n-1).
- *
- * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
- * an power value of -1. So we use -2, -3, etc, for other
- * c-states.
- */
- if (!drv->power_specified) {
- for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++)
- drv->states[i].power_usage = -1 - i;
- }
-}
-
-
/**
* cpuidle_register_driver - registers a driver
* @drv: the driver
@@ -58,7 +34,6 @@ int cpuidle_register_driver(struct cpuidle_driver *drv)
spin_unlock(&cpuidle_driver_lock);
return -EBUSY;
}
- __cpuidle_register_driver(drv);
cpuidle_curr_driver = drv;
spin_unlock(&cpuidle_driver_lock);

diff --git a/drivers/cpuidle/governors/ladder.c b/drivers/cpuidle/governors/ladder.c
index b6a09ea..2e7ea8c 100644
--- a/drivers/cpuidle/governors/ladder.c
+++ b/drivers/cpuidle/governors/ladder.c
@@ -79,9 +79,9 @@ static int ladder_select_state(struct cpuidle_driver *drv,

last_state = &ldev->states[last_idx];

- if (drv->states[last_idx].flags & CPUIDLE_FLAG_TIME_VALID) {
+ if (dev->state_parameters[last_idx].flags & CPUIDLE_FLAG_TIME_VALID) {
last_residency = cpuidle_get_last_residency(dev) - \
- drv->states[last_idx].exit_latency;
+ dev->state_parameters[last_idx].exit_latency;
}
else
last_residency = last_state->threshold.promotion_time + 1;
@@ -89,7 +89,7 @@ static int ladder_select_state(struct cpuidle_driver *drv,
/* consider promotion */
if (last_idx < drv->state_count - 1 &&
last_residency > last_state->threshold.promotion_time &&
- drv->states[last_idx + 1].exit_latency <= latency_req) {
+ dev->state_parameters[last_idx + 1].exit_latency <= latency_req) {
last_state->stats.promotion_count++;
last_state->stats.demotion_count = 0;
if (last_state->stats.promotion_count >= last_state->threshold.promotion_count) {
@@ -100,11 +100,12 @@ static int ladder_select_state(struct cpuidle_driver *drv,

/* consider demotion */
if (last_idx > CPUIDLE_DRIVER_STATE_START &&
- drv->states[last_idx].exit_latency > latency_req) {
+ dev->state_parameters[last_idx].exit_latency > latency_req) {
int i;

for (i = last_idx - 1; i > CPUIDLE_DRIVER_STATE_START; i--) {
- if (drv->states[i].exit_latency <= latency_req)
+ if (dev->state_parameters[i].exit_latency <=
+ latency_req)
break;
}
ladder_do_selection(ldev, last_idx, i);
@@ -136,12 +137,12 @@ static int ladder_enable_device(struct cpuidle_driver *drv,
int i;
struct ladder_device *ldev = &per_cpu(ladder_devices, dev->cpu);
struct ladder_device_state *lstate;
- struct cpuidle_state *state;
+ struct cpuidle_state_parameters *state_parameters;

ldev->last_state_idx = CPUIDLE_DRIVER_STATE_START;

for (i = 0; i < drv->state_count; i++) {
- state = &drv->states[i];
+ state_parameters = &dev->state_parameters[i];
lstate = &ldev->states[i];

lstate->stats.promotion_count = 0;
@@ -151,9 +152,11 @@ static int ladder_enable_device(struct cpuidle_driver *drv,
lstate->threshold.demotion_count = DEMOTION_COUNT;

if (i < drv->state_count - 1)
- lstate->threshold.promotion_time = state->exit_latency;
+ lstate->threshold.promotion_time =
+ state_parameters->exit_latency;
if (i > 0)
- lstate->threshold.demotion_time = state->exit_latency;
+ lstate->threshold.demotion_time =
+ state_parameters->exit_latency;
}

return 0;
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 0633575..e9bbc20 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -281,7 +281,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
* unless the timer is happening really really soon.
*/
if (data->expected_us > 5 &&
- drv->states[CPUIDLE_DRIVER_STATE_START].disable == 0)
+ dev->state_parameters[CPUIDLE_DRIVER_STATE_START].disable == 0)
data->last_state_idx = CPUIDLE_DRIVER_STATE_START;

/*
@@ -289,7 +289,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
* our constraints.
*/
for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
- struct cpuidle_state *s = &drv->states[i];
+ struct cpuidle_state_parameters *s = &dev->state_parameters[i];

if (s->disable)
continue;
@@ -336,7 +336,8 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
struct menu_device *data = &__get_cpu_var(menu_devices);
int last_idx = data->last_state_idx;
unsigned int last_idle_us = cpuidle_get_last_residency(dev);
- struct cpuidle_state *target = &drv->states[last_idx];
+ struct cpuidle_state_parameters *target =
+ &dev->state_parameters[last_idx];
unsigned int measured_us;
u64 new_factor;

diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
index 88032b4..7b17413 100644
--- a/drivers/cpuidle/sysfs.c
+++ b/drivers/cpuidle/sysfs.c
@@ -215,9 +215,10 @@ static struct kobj_type ktype_cpuidle = {

struct cpuidle_state_attr {
struct attribute attr;
- ssize_t (*show)(struct cpuidle_state *, \
- struct cpuidle_state_usage *, char *);
- ssize_t (*store)(struct cpuidle_state *, const char *, size_t);
+ ssize_t (*show)(struct cpuidle_state *, struct cpuidle_state_usage *,
+ struct cpuidle_state_parameters *, char *);
+ ssize_t (*store)(struct cpuidle_state_parameters *, const char *,
+ size_t);
};

#define define_one_state_ro(_name, show) \
@@ -228,13 +229,15 @@ static struct cpuidle_state_attr attr_##_name = __ATTR(_name, 0644, show, store)

#define define_show_state_function(_name) \
static ssize_t show_state_##_name(struct cpuidle_state *state, \
- struct cpuidle_state_usage *state_usage, char *buf) \
+ struct cpuidle_state_usage *state_usage, \
+ struct cpuidle_state_parameters *state_parameters, \
+ char *buf) \
{ \
- return sprintf(buf, "%u\n", state->_name);\
+ return sprintf(buf, "%u\n", state_parameters->_name);\
}

#define define_store_state_function(_name) \
-static ssize_t store_state_##_name(struct cpuidle_state *state, \
+static ssize_t store_state_##_name(struct cpuidle_state_parameters *state, \
const char *buf, size_t size) \
{ \
long value; \
@@ -253,14 +256,18 @@ static ssize_t store_state_##_name(struct cpuidle_state *state, \

#define define_show_state_ull_function(_name) \
static ssize_t show_state_##_name(struct cpuidle_state *state, \
- struct cpuidle_state_usage *state_usage, char *buf) \
+ struct cpuidle_state_usage *state_usage, \
+ struct cpuidle_state_parameters *state_parameters, \
+ char *buf) \
{ \
return sprintf(buf, "%llu\n", state_usage->_name);\
}

#define define_show_state_str_function(_name) \
static ssize_t show_state_##_name(struct cpuidle_state *state, \
- struct cpuidle_state_usage *state_usage, char *buf) \
+ struct cpuidle_state_usage *state_usage, \
+ struct cpuidle_state_parameters *state_parameters, \
+ char *buf) \
{ \
if (state->_name[0] == '\0')\
return sprintf(buf, "<null>\n");\
@@ -298,6 +305,7 @@ static struct attribute *cpuidle_state_default_attrs[] = {
#define kobj_to_state_obj(k) container_of(k, struct cpuidle_state_kobj, kobj)
#define kobj_to_state(k) (kobj_to_state_obj(k)->state)
#define kobj_to_state_usage(k) (kobj_to_state_obj(k)->state_usage)
+#define kobj_to_state_parameters(k) (kobj_to_state_obj(k)->state_parameters)
#define attr_to_stateattr(a) container_of(a, struct cpuidle_state_attr, attr)
static ssize_t cpuidle_state_show(struct kobject * kobj,
struct attribute * attr ,char * buf)
@@ -305,10 +313,12 @@ static ssize_t cpuidle_state_show(struct kobject * kobj,
int ret = -EIO;
struct cpuidle_state *state = kobj_to_state(kobj);
struct cpuidle_state_usage *state_usage = kobj_to_state_usage(kobj);
+ struct cpuidle_state_parameters *state_parameters =
+ kobj_to_state_parameters(kobj);
struct cpuidle_state_attr * cattr = attr_to_stateattr(attr);

if (cattr->show)
- ret = cattr->show(state, state_usage, buf);
+ ret = cattr->show(state, state_usage, state_parameters, buf);

return ret;
}
@@ -317,11 +327,12 @@ static ssize_t cpuidle_state_store(struct kobject *kobj,
struct attribute *attr, const char *buf, size_t size)
{
int ret = -EIO;
- struct cpuidle_state *state = kobj_to_state(kobj);
+ struct cpuidle_state_parameters *state_parameters =
+ kobj_to_state_parameters(kobj);
struct cpuidle_state_attr *cattr = attr_to_stateattr(attr);

if (cattr->store)
- ret = cattr->store(state, buf, size);
+ ret = cattr->store(state_parameters, buf, size);

return ret;
}
@@ -369,6 +380,7 @@ int cpuidle_add_state_sysfs(struct cpuidle_device *device)
goto error_state;
kobj->state = &drv->states[i];
kobj->state_usage = &device->states_usage[i];
+ kobj->state_parameters = &device->state_parameters[i];
init_completion(&kobj->kobj_unregister);

ret = kobject_init_and_add(&kobj->kobj, &ktype_state_cpuidle, &device->kobj,
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 6c26a3d..cddbd34 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -42,12 +42,6 @@ struct cpuidle_state {
char name[CPUIDLE_NAME_LEN];
char desc[CPUIDLE_DESC_LEN];

- unsigned int flags;
- unsigned int exit_latency; /* in US */
- int power_usage; /* in mW */
- unsigned int target_residency; /* in US */
- unsigned int disable;
-
int (*enter) (struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index);
@@ -55,6 +49,14 @@ struct cpuidle_state {
int (*enter_dead) (struct cpuidle_device *dev, int index);
};

+struct cpuidle_state_parameters {
+ unsigned int flags;
+ unsigned int exit_latency; /* in US */
+ int power_usage; /* in mW */
+ unsigned int target_residency; /* in US */
+ unsigned int disable;
+};
+
/* Idle State Flags */
#define CPUIDLE_FLAG_TIME_VALID (0x01) /* is residency time measurable? */

@@ -83,6 +85,7 @@ cpuidle_set_statedata(struct cpuidle_state_usage *st_usage, void *data)
struct cpuidle_state_kobj {
struct cpuidle_state *state;
struct cpuidle_state_usage *state_usage;
+ struct cpuidle_state_parameters *state_parameters;
struct completion kobj_unregister;
struct kobject kobj;
};
@@ -96,7 +99,7 @@ struct cpuidle_device {
int state_count;
struct cpuidle_state_usage states_usage[CPUIDLE_STATE_MAX];
struct cpuidle_state_kobj *kobjs[CPUIDLE_STATE_MAX];
-
+ struct cpuidle_state_parameters state_parameters[CPUIDLE_STATE_MAX];
struct list_head device_list;
struct kobject kobj;
struct completion kobj_unregister;
--
1.7.7.rc0.72.g4b5ea.dirty


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